Photographic copying, enlarging, and reducing apparatus



Juhe 9, 1925. 1,541,214

, R. HARRIS PHOTOGRAPHIC COPYING, ENLARGING, AND REDUCING APPARATUSFiled April 1, 1924 2 Sheets5haet 1 0' (Mel? I l MM WW I 1 1 1 MIG F1 la :1" '1. M a

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Patented June 9, 1925.

UNITED STATES I 1,541,214 PATENT OFFICE. 1

ROBERT HARRIS, OF LONDON, ENGLAND, ASSIGNOB OF ONE-HALF T0 PIC'I'OBIAIIMACHINERY LIMITED, 0]? LONDON, ENGLAND, A BRITISH COMPANY.

PHOTOGRAPHIC COPYING, ENLARGING, AND REDUCING APPABATO'B.

Application filed April 1,

To allwhom it may concern 'Be it known that I, ROBERT HARRIS, a subjectof the King of England, residing-at London, En land, have inventedcertain new and useful mprovements in Photographic Copying, Enlargin andReducing Aparatus, of which t e following is a specication.

This invention is for improvements in or relating to photographiccopying. enlarging and reducing apparatus, and relates more particularlyto ste -and-repeat machines in which an image is automaticallymaintained in focus upon a screen as the degree of enlargement isvaried.

The type of ste -and-repeat machine to which this invention relatescomprises a unit-holder, a lens holder and an imagescreen mounted upon afixed framework, one of the said components being fixed to the frameworkand the other being arran ed to be movable relativelythereto at suchifl'er ent rates as automatically to maintain an image in correct"focus.

The invention has for its main object to provide improved mechanism foreffecting the automatic adjustment of the focus of the I image on thescreen when the size of the image is varied.

According to a primary feature of this invention, a step-and-repeatmachine of the ty e comprising an object-holder, .a lensho der and anlmage-screen mounted upon a fixed framework. one of the said componentsbeing fixed to the frame-work and the others being arranged to bemovable relatively thereto at such different rates as automaticallv tomaintain an image in correct focus, is characterized in that theimage-screen is fixed to the framework, a

.movable table on the framework carries the unit-holder and lens-holder,one of which latter components is fixed thereon and the otheris-movable, and in the provision of means carried by the said table andoperatively connected to the movable component and to the fixedframework to effect auto- 1984. Serial No. 703,418.

maintainin contact with the cam.

According to a further feature of this invention, the teeth of thecam-pinion and rack are arranged at such an angle to the axis of the camthat the normal pitch is a standard pitch.

A further feature of the invention consists in mounting the rack on theframework so that it may be adjustable in an endwise the said movablecomponent in direction. With this arrangement the focus of theapparatus, may be adjusted at any time by t e movement of the said rack.

For a more complete understanding of the invention there will now bedescribed by way of example only and with reference to the accompanyingdrawings, one'constructional form of step-and-repeat machine accordingto the present invention. In said drawings:

Figure 1 1s a erspective view of a step- :nd-repeat machlne according.to the inven- 1011,

Figure 2 is a perspective view of part of the projector comprising alens-holder and unit-carrier, but on a scale larger than'that of Figure1,

Figure 3 is a vertical transverse section taken through the base of thelens-holder,

and-

Fi ire 4 is a plan view of a cam. Li e reference characters designatelike parts throughout the several views.

Referring to the drawings, a main frame having the form of an inverted Ucomprises a base A and two vertical standards A. A horizontally disposedframework B is mounted on three feet B adjustable in height secured tothe base A. This framework B extends from a line near the middle of thestandards A to the front of the machine beyond the front end of thebase."

A stage C for an image screen is so mounted on the rear of the standardsA as to be movable both in vertical and transverse directions.

A table D is arran d to slide.along a horizontal track provi ed on thetop of the framework B. This table D can be moved along the said tracktowards or away from the screen by mechanism comprising a rack D and ahand-operated pinion K meshing therewith.

A ro ector com rises a lens-holder E, a unitolcer F an a lantern G whichis mounted on a two-wheeled trolley G pivotally connected at G to theunit-holder F and arranged to run on the top of the framework B.

The unit-holder F comprises a main frame F adjustably attached to a baseF having rollers F arranged to run on trackways along the top of thetable D in a direction towards and away from the screen. The frame F ofthe unit-holder has a tongue and groove connection with the base F sothat 1t can be adjusted thereon in the direction towards and away fromthe screen.

The lens-holder E comprises a pedestal E and an open-sided hollow base Ewhich adjustable along the table D and is normally fixed thereto by astud as shown at E The pedestal E has a tongue-andgroove connection withits base E so that it can be adjusted thereon in the same direction asthe frame F of the unit-holder F on its base F, studs being provided forsecuring the parts in their adjusted positions. I

As shown in Figure 3, a vertical spindle H 'is journalled in thebottom'of the base E and carries a cam H at its upper end in thethroughway of the base. The spindle extends down through the table Dinto the framework B where it carries a pinion H that meshes with a rackH mounted on the inside of the framework B. This rack is slidable in thedirection of its length on the frame B and can be fixed in position bymeans of set-screws H. The cam H, which is of the shape shown in plan inFigure 4., can extend out of the throughway of the base E and contactswith a vertically disosed anti-friction roller F carried on the ase F ofthe unit-holder F. This base F is constantly drawn towards the cam H bya cord J which runs over a pulley J on the end of the table D andcarries a weight J movable vertically inside the framework B. eoperation of the apparatus described above is as follows:

When it is desired to enlarge or decrease the image thrown by theprojector on the screen, the table D is traversed along the frame-workBby the hand-operated rackand-pinion mechanism D K and the unit holder Fand lens-holder E move with the table. The movement of the table D onthe framework B causes the pinion H and the cam H to be rotated by therack H, and the unit-holder F is thus moved relatively to V thelens-holder E. The profile of the cam H is so designed that themovements of the lens-holder and unit-holder in relation to the screenmaintain the image in focus in all positions of the table D. By shiftingthe rack H endwise the apparatus may be focused at any time.

In determining the contour of the cam H the required maximum and minimumdegree of enlargement and the focal length of the lens in thelens-holder E are first selected. The extent of the movement of thetable D towards and awayfrom the screen can then be calculated, as alsocan the extent of the movement of the unit-holder F towards and awayfrom the lens-holder E. Preferably a complete revolution of the cam Hproduces the required movement of the unit-holder, and thus the totallift of the cam is equal to the extent of the latter movement. Since thecam H makes one revolution in producing this movement, the pitch-circlecircumference of the cam-pinion H must be equal to the distancetraversed by the table. It is found in practice that owing to beinglimited to a fixed pitch-circle circumference, a standard pitch ve oftencannot be used, stand ard pitc meaning the distance measured above thepitch circle, from the middle of one tooth to the middle of the nexttooth of a pinion or rack having teeth-parallel to the axis of the thedirection of length of the rack, which teeth can be cut with a standardcutter. This is because such standard pitch may not have the requiredexact whole number of teeth, without any fraction of a tooth, tocorrespond to the said distance to be traversed by the table. Toovercome this difiiculty a number of teeth is selected giving thenearest pitch to the standard and the teeth are arranged askew at suchan angle to the axis of the pinion that the pinion has a normalpitch, 1. e., the pitch measured perpendicular to the skew teeth, whichis equal to the standard pitch of a like pinion having teeth parallel toits axis. Consequently, the skew gear and corresponding rack having anormal pitch equal to standard pitch can be used.

It is to be understood that various modifications may be made in theconstruction described above without departing from the scope of theinvention as defined in the claims; for example, instead of a wei ht aspring may be used for keeping the ro er F in contact with the cam H.

What I claim as m invention and desire to secure by Letters atent is:

In a step-and-repeat machine, the combination of a fixed framework, aunit holder a lens holder and an image screen mounted thereon, one ofwhich com onents is fixed and the other two arrange to be movablerelatively thereto, and automatic means whereby-the movement of the onemovable component so automatically controls the movement of the secondmovable component as to maintain an image in correct focus on thescreen, which means comprises a toothed rack on the framework, a camrotatably carried by one movable component, a pinion oppinion or atright angles toa pinion or rack of holder,

eratively connected with said cam and meshlng ing the second movablecomponent in contact with said cam, the teeth of which pinion and rackare arranged at such an angle to the axis of rotation of the cam thatthe normal pitch is a standard pitch.

2. In a step-and-repeat machine, the combination with a fixed framework,an image screen fixed thereon, a table movable on said framework towardsand away from said screen, a lens-holder and a unit-holder so mounted onsaid table that the lens-holder is located between the screen and theunitone of which holders is fixed and the other is movable on saidtable, and means for automatically adjusting the movable holder inrelation to the fixed holder when said table is moved along theframework, which means comprise a toothed rack on the framework, a camrotatably carried by said table, a pinion operatively connected withsaidcam and meshin with said rack, and means for maintaining the movableholder in contact with said cam when the table is moved along theframework, the teeth of which pinion and rack are arranged with saidrack, and means for maintain-' at such an angle to the axis of rotationof the cam that the normal pitch is a standard pitch.

3. In a step-and-re eat machine, the combination with a fixe framework,an image screen fixed thereon, a table movable on said framework towardsand away from said screen, a lens-holder and a unit-holder so mounted onsaid'table that the lens-holder is located between the screen and'theimitholder, one of which holders is fixed and the other is movable onsaid table, and means for automatically adjusting the movable holdcr inrelation to the fixed holder when said table is moved along theframework, which means comprise a toothed rack mounted to be adjustableendwise on the framework, a cam rotatably carried by said table, apinion operatively connected with said cam and meshing with said rack,and means for maintaining the movable holder in contact with said camwhen the table is moved along the framework.

In testimony whereof I afiix my signature.

, ROBERT HARRIS.

